Field of the Invention
This invention relates, in general, to the construction of fuel pumps and, in particular, to a new and useful electromagnetically operated fuel piston pump having an improved sealing arrangement.
The invention particularly refers to an electromagnetactuated fuel piston pump, especially for heating equipment operating on liquid fuel, in which an electromagnetically reciprocating piston delivers the fuel from a cylindrical space through a bore arranged in a cylinder, and at the downstream end of the cylinder there is a spring-loaded pressure valve, followed by a pressure pipe joint further downstream.
Such fuel piston pumps are used preferably for small heating appliances, suitable for installation in motor vehicles, or for small stationary heating layouts.
Fuel piston pumps of a similar kind are already known. Thus, German patent No. 23 15 842 describes a fuel piston pump of this category, in which the fuel is delivered by piston, driven back and forth by an electromagnet, from a cylindrical space into the bore of a pressure pipe joint. In this familiar arrangement, at the end of each stroke the piston strikes against the pressure pipe joint, resulting in a loud knocking noise. The metallic connection of the pressure pipe joint to the pump housing amplifies the emission of the noise, which is very distracting.
Efforts to dampen the disturbing knocking noises by an acoustic separation of the structural components have produced no satisfactory result. There has also been an attempt to reduce the noise by arrangement of an elastic stop plate on the end of the cylinder facing the cylindrical space and, consequently, the piston. However, it turned out that the known materials are not resistant to the delivered fuel, but instead swell up or even dissolve.